Fire extinguishers should be inspected annually - by a suitably qualified person.
once a month :)
Commercially speaking, in the UK they have to be checked annually, and signed.
Depending upon what fire code is used and where the extinguisher is located, it should be checked monthly. In fact, a fire inspector can ask to see the records of the monthly tests, which are normally attached on a tag on each extinguisher. Modern codes are beginning to require automatic electronic monitoring of fire extinguishers.
Yearly
DailyDaily
monthly
brake linings should be checked at 15,000 and 25,000 miles and then every 5,000 miles after that.
Flammable metals often require special chemicals to extinguish, assuming there are any. So, in fact, you WOULD use a "chemical extinguisher", but probably not an ordinary dry chemical extinguisher.
Every time it is worn!
With each brake job.
Every time it is worn.
Every time the PFD is worn
every 4 weeks in the community